A viewer's guide to watching Tuesday's election returns

WASHINGTON — Watch Virginia and West Virginia as the early election returns come in Tuesday night. Then keep an eye on South Carolina. Of states where polls close first, those three have Democrats viewed as most vulnerable.

Should West Virginia Gov. Joe Manchin lose his Senate bid to Republican John Raese for the seat Democratic icon Robert Byrd held for 52 years until he died in June, it will be seen as a sign that the GOP surge is starting to build.

In Virginia, moderate House of Representatives Democrats Glenn Nye and Tom Perriello are considered vulnerable; if they survive, Republicans could fare less well nationally than expected.

On the other hand, if House Budget Committee Chairman John Spratt, D-S.C., loses the seat he first won in 1982, that could mean that the GOP is poised for huge gains in the House.

Republicans must gain 39 House seats and 10 Senate seats to take control of each chamber. Analysts and polls suggested Monday that when all results are in, the GOP is likely to control the House and come close to winning a Senate majority.

"There are really only two choices: a big wave or a medium-sized wave," said Larry Sabato, the director of the Center for Politics at the University of Virginia.

At stake are all 435 House seats, 37 Senate seats and 37 governorships.

The Cook Political Report, a respected nonpartisan analyst, predicted Monday that Republicans would gain 50 to 60 House seats and six to eight Senate seats, which was in line with most leading forecasters.

Much depends on voter turnout, and for months polls have found Republicans more eager to head to the polls than Democrats.

Lee Miringoff, the director of the Marist Institute for Public Opinion in New York, detected some last-minute rallying by Democrats in last week's McClatchy-Marist polls in four key states: Wisconsin, Colorado, Pennsylvania and Washington. However, he said, the trend didn't appear strong enough to deliver significant momentum to Democratic candidates.

Polls begin closing at 6 p.m. EDT in Indiana and Kentucky. Virginia, South Carolina and parts of Florida are among those that close an hour later, and West Virginia voting ends at 7:30 p.m. EDT.

After that, closings come quickly. Other races and trends to watch:

- 8 p.m. EDT. Look for the first evidence of the national mood as polls close in most East Coast and Midwestern states.

Democrats could face big trouble retaining their Senate majority if they lose races in Connecticut, to former wrestling executive Linda McMahon, and in Delaware, to controversial conservative commentator Christine O'Donnell, seats now held by retiring Democrats.

A Pennsylvania win by Democratic Rep. Joe Sestak over former Rep. Pat Toomey, a Republican, would hurt the GOP's chances to take over the Senate. Sabato calls that race "the first indication that matters," since it's considered a tossup.

To take the Senate, Republicans also need a victory in Illinois by Rep. Mark Kirk over Democrat Alexi Giannoulias for the seat that President Barack Obama once held.

In House races, any Republican wave should emerge in this hour, as several moderate Democrats face tough challenges in the region. Some centrist Democrats to watch: veterans such as Mississippi's Gene Taylor, Missouri's Ike Skelton and Florida's Allen Boyd, and freshmen including Pennsylvania's Kathy Dahlkemper, Alabama's Bobby Bright, Maryland's Frank Kratovil, and Florida's Alan Grayson and Suzanne Kosmas.

"There are always anomalies, and people should be wary of making rash judgments because one House races goes one way or that way," Sabato said. "You've got to wait to get the results from the whole East Coast. If Republicans are up 10-12 seats, they're taking over. If they're only up four, then it will be a long night."

- 9 p.m. EDT. Between 9 and 10 p.m., it should become clear which party will control the next Congress.

Two more Democratic-held Senate seats could change hands. Three-term incumbent Wisconsin Democratic Sen. Russell Feingold trails Republican Ron Johnson in the latest polls, while the Colorado race between Republican Ken Buck and Democratic Sen. Michael Bennet is too close to call. Both states' polls close at 9 p.m. EDT.

Several House seats long held by Democrats are also in play; should Republicans win them, it's more evidence of a huge sweep. Among the GOP targets are seats now held by House Appropriations Committee Chairman David Obey of Wisconsin, who's retiring after 41 years, and Rhode Island's Patrick Kennedy, also retiring, as well as the seat held by rising Democratic star Stephanie Herseth Sandlin of South Dakota.

- 10 p.m. EDT. Polls close in Nevada, ending the too-close-to-call duel between Senate Democratic leader Harry Reid and Republican tea party favorite Sharron Angle. The race brims with symbolism: How strong is the tea party movement? Have Reid and his leadership been repudiated?

- 11 p.m. EDT and beyond. Should control of Congress still be up for grabs at this hour, some tight races will be watched closely.

In California, Sen. Barbara Boxer appears to have pulled ahead in her battle with former Hewlett-Packard executive Carly Fiorina. In Washington state, Sen. Patty Murray has been in a virtual tie with Republican Dino Rossi.

The night's final act is likely to come from Alaska, where incumbent Sen. Lisa Murkowski is waging a write-in campaign against Republican Joe Miller, who beat her in the primary, and Democrat Scott McAdams.